Endoscopic bite block

ABSTRACT

There is provided herein, a bite block ( 100 ) comprising an insertion channel ( 134 ) and an airway channel ( 132 ) wherein the airway channel is adapted to receive exhaled breath and wherein the first insert channel is adapted to pass a medical instrument. There is provided herein, a bite block comprising an oral insert channel, wherein a portion of said channel opens into a cavity ( 142 ) adapted to slidably receive an oral prong ( 270 ) the oral insert channel is adapted to receive exhaled breath.

FIELD

The invention relates to medical appliances.

BACKGROUND

Numerous medical procedures require the insertion of an instrument, suchas an endoscope, down a person's mouth and into the body. Such is thecase when performing, for example, an Esophagogastroduodenoscopy (EGD),a procedure comprising the insertion of a flexible endoscope through themouth until reaching the duodenum (first and shortest part of the smallintestine). The endoscope when inserted is used to provide a visualinspection of the organs, and optionally to perform medical proceduressuch as, for example, biopsies, incisions, and retrieval of foreignobjects.

Endoscopic procedures are usually performed while a patient is undertopical or moderate sedation, although in some circumstances it may beperformed while the patient is under general anesthesia. During moderatesedation or general anesthesia the patient is generally sedatedintravenously to minimize gagging and to facilitate the procedure. Abite block is used to prevent the patient from biting on the endoscope,to facilitate the introduction of the endoscope into the mouth, and tomaneuver the endoscope relatively freely while inserted in the mouth.

A frequent occurrence when administering intravenous sedation is reducedbreathing in the patient, which may lead to hypoxia, or a reduction ofoxygen in the blood. It is then substantially common practice toadminister oxygen or another breathable gas to the patient, usuallythrough a nasal cannula, while the patient is sedated. Additionally, thepatient's exhaled breath is typically monitored, by means of acapnograph, in order to corroborate that the patient's carbon dioxidelevels in the blood and the tissues are within safe limits.

A number of bite blocks have been adapted with features to supplyoxygen, or optionally some other type of breathable gas, to a sedatedpatient. Some have been further adapted with features which allow thepatient to be connected to a capnograph for measuring the carbon dioxidecontents in the patient's exhaled breath. The following patents and/orpublications describe different types of bite blocks adapted with someof these features, all of which are incorporated herein by reference.

U.S. Pat. No. 5,273,032 “Oxygenating Oral Medical Appliance”, describesan “endoscopic mouth guard having a smoothly contoured, waisted tubemerging into a peripheral flange at the front end of said tube, amanifold integral with the front face of said flange defining a closedended, transverse distribution duct, and two open ended, upwardlydirected branch ducts ending, in use, closely below the nostrils of apatient fitted with the guard, two further, open ended branch ductsextending rearwardly from said distributor duct into the bore of saidtube, and a laterally and rearwardly directed tapered spigot on saidmanifold, defining an extension of said distributor duct, adapted toenter the bore of a gas supply tube. The finished guard is a singlearticle of plastics material having a smooth hard surface.”

U.S. Pat. No. 5,513,634 “Combination Integral Bite Block Airway andNasal Cannula”, describes a “combination plastic relatively rigid biteblock and soft nasal cannula intended for one-time use for supplyingoxygen to a patient's nostrils during an endoscopic procedure. Thecannula is fixed into the bite block by an integral clip portion of thecannula extending downwardly from a manifold portion and adhered to thebite block. Flexible nasal prongs extend upwardly from the manifold intothe patient's nostrils to supply supplementary gas separately from airbreathed through the patient's mouth.”

US Patent Application Publication No. US 2007/0006878 A1“Capnographic-oxygenating Oro-fiberscopic Bite block”, describes anoro-fiberscopic bite block. “The bite block is utilized during oralfiberscopic procedures. The bite block includes a main structure havingan orifice sized to accommodate entry of a fiberscope, such as anendoscope, through the orifice. The bite block includes an extensionextending inward from the main structure when positioned within themouth of a patient. On each side of the orifice is a loop for handlingand positioning the bite block within the patient's mouth. The biteblock includes an exhalation tube running from the extension to amonitoring device which allows monitoring of the patient's expelledgases. In addition, an inhalation tube may be used to providesupplemental oxygen to the patient. The bite block is positioned in themouth of the patient with the mouth of the patient surrounding theextension. The tubes include openings which are located on the extensionand lie in the interior of the mouth to provide monitoring ofuncontaminated gasses expelled by the patient.”

PCT International Application Publication No. WO 2007/063532 “EndoscopicBite Block”, describes a “bite block assembly adapted for capnographyand oxygen delivery to a subject, the bite block assembly including afirst capnography passageway adapted for passage therethrough of exhaledbreath from the subject to a capnograph and a second oxygen deliverypassageway, separate from the first passageway, adapted for passagetherethrough of oxygen from an oxygen source to the mouth of thesubject.”

There is still a need in the art for improved bite blocks, systemsincluding them and methods that would allow efficient breath samplingduring medical procedures such as endoscopy.

SUMMARY

An aspect of some embodiments of the invention relates to a device, suchas a bite block device, a system, such as a bite block and an oral nasalbreath sampling cannula, and method for sampling breath, for example forthe purpose of capnographic measurements, while performing a medicalprocedure such as insertion of an endoscope. In addition, the device mayalso include oxygen delivery element(s).

Since experience has shown that patients have a tendency to breaththrough their mouth during a procedure such as endoscopy, according tosome embodiments, the device, system and method provide oxygen deliveryand oxygen flow regulation means that facilitate the direction of theoxygen flow to the mouth and/or to the nose as needed and/or whenneeded. For example, when the bite block is in place the system isadapted to provide more oxygen to the mouth or even, only to the mouth.However, when the bite block is not in a patient's mouth the system isadapted to provide more oxygen to the nose or even, only to the nose. Inaddition, in many of the existing bite blocks adapted to deliver oxygenand allow capnographic measurements, problems have been encounteredassociated with the oxygen being delivered at a relatively higherpressure than that at which the exhaled breath is expelled by thepatient. The higher pressure, at which the oxygen is delivered orallyand/or nasally, occasionally forces the exhaled breath away from anentrance to exhaled breath collection means or allows oxygen into thesampling tubes. For example, when a patient is lightly breathing throughthe nose or not breathing through the nose at all, during endoscopy ordue to any other reason, the collection of the exhaled breath may bediluted with the supplied oxygen, which affects the accuracy of thecapnographic measurements. Another example may be during medicalprocedures known as MAC, monitoring anesthesia care, where U.E.procedures are performed using high levels of oxygen, typically inexcess of 5 l/min. According to some embodiments, the device, system andmethod are adapted to improve breath sampling and to reduce dilution ofthe sampled breath with oxygen. Furthermore, thedevice, system andmethod are adapted to provide high oxygen delivery, optionally at ratesup to 10 L/min.

According to an aspect of some embodiments of the invention, orallydelivered oxygen or optionally, any other breathable gas, delivered at arelatively high pressure, is substantially prevented from interferingwith the free flow of orally exhaled breath, by separately channelingthe oxygen through an oxygen channel and the exhaled breath through anairway channel, and by maintaining a substantial distance between theopenings to these channels. The pressure of the oxygen at an opening ofthe airway channel is less than the pressure of the opposing exhaledbreath and therefore, oxygen is substantially prevented from enteringthe airway channel and diluting the exhaled breath. Additionally, theoxygen channel may include a relatively large aperture at one endthrough which the oxygen flows from the oxygen channel into the back ofthe patient's mouth. The use of a relatively large aperture causes apressure decrease in the flow of oxygen when exiting from the oxygenchannel. Optionally, more than one oxygen channels may be used.Additionally or alternatively, the oxygen channel or channels mayinclude several apertures. The distance between the two channel openingsmay be determined by the pressure at which the oxygen exits the oxygenchannel in the bite block. For example, the airway channel may bedesigned to extend inwardly to the direction of the mouth of the patientrelative to the oxygen channel. Optionally, the oxygen channel may bedesigned such that the oxygen flow is not directly in the direction intothe back of the mouth of the patient, for example, slanted downwards. Inthis manner, an efficient collection of exhaled breath for capnographicmeasurements may be maintained while substantially high oxygen deliveryis performed. In some embodiments of the invention, the oxygen channelmay comprise one or more apertures in the insertion channel throughwhich oxygen, or optionally a portion of the delivered oxygen, may flowout of the oxygen channel into the patient's mouth.

In accordance with some embodiments of the invention, there is provideda bite block including an insertion channel through which a medicalinstrument, for example, an endoscope, may be inserted into the mouth ofthe patient. The bite block may further include an airway channel, whichextends further into the mouth of the patient relative to the oxygenchannel and to the insertion channel. In some embodiments of theinvention, an opening may extend partially or entirely, along the lengthbetween the airway channel and the insertion channel. The bite block mayalso include an oxygen channel through which oxygen is delivered to thepatient. The exhaled breath may freely flow through the airway channeltowards a sampling port connected to the capnograph. The oxygen channelmay be formed along a side of the insertion channel for patient comfort.Alternatively, the oxygen channel may be positioned in the bite block inany manner which permits high oxygen delivery, the distance between theairway channel and the oxygen channel preferably not less than thedistance between the airway channel and the insertion channel.

In some embodiments of the invention, the bite block comprises anextendable oral nasal cannula, which is substantially maintained insidethe patient's nostrils generally independent of the patient's headposition and of movement of the bite block. The airway channel opensinto a cavity in a forward section of the bite block, external to thepatient's mouth. An oral prong in the oral nasal cannula is adapted toslide in a generally lateral direction along a z-axis back and forthalong the cavity, and to rotate and tilt relative to a y-axissubstantially perpendicular to the direction of sliding, in order tocompensate for movement of the bite block relative to the patient'smouth. Additionally, the oral prong is adapted to slidingly extend inand out of an oral prong extension in a generally vertical directionalong the y-axis substantially extending the length of the oral prong. Alarge degree of freedom of movement in the oral prong, and thereby inthe oral nasal cannula, substantially reduces the possibility that thenasal prong may slip out of the bite block due to movement of the biteblock relative to the patient's mouth. As a result, substantiallycontinuous flow of exhaled breath is maintained to the capnograph. Insome embodiments of the invention, the bite block comprises an airwaychannel which includes an opening to which the oral prong is affixed.Exhaled breath may then flow through the opening in the airway channelinto the oral prong. In some embodiments of the invention, the biteblock may include an oral prong as an integral part of the bite block.The oral prong may be connected to one or more nasal prongs. Theintegral oral prong may open into a roof of the airway channel.

In addition, according to some embodiments, the device and system may beadjustable to fit different patients.

In accordance with an embodiment of the invention, there is provided abite block comprising an insertion channel and an airway channel,wherein the airway channel is adapted to pass substantially free flow ofbreath, and wherein the insertion channel is adapted to passsubstantially free flow of breath and to pass a medical instrument.Optionally, a portion of the airway channel opens into a cavity adaptedto receive an oral prong, wherein the oral prong is adapted to samplebreath from a patient. Optionally, the cavity is further adapted toallow relative motion between the bite block and the prong withoutsubstantially reducing the breath sampling.

In accordance with some embodiments of the invention, the airway channelis adapted to receive an oral prong, wherein the oral prong is adaptedto sample breath from a patient.

In accordance with some embodiments of the invention, the airway channelis adapted to pass substantially free flow of breath through a duct.Optionally, the duct is further adapted to enable a viewer to view theposition of an oral prong functionally connected to the bite block.

In accordance with some embodiments of the invention, the bite blockfurther comprises an oxygen channel located in proximity to theinsertion channel, wherein the oxygen channel is adapted to directoxygen towards the inside of the mouth of a patient. Optionally, theairway channel is adapted to protrude further into the back of the mouthrelative to the insertion channel and/or the oxygen channel.Additionally or alternatively, the bite block is adapted to reduce theflow of oxygen from the oxygen channel into the airway channel, suchthat the oxygen pressure is adapted to be lower than the opposingpressure created by the exhaled breath, so that the exhaled breath canpush back out of the mouth the oxygen, and at least partially preventoxygen from reaching the airway channel opening and consequentlydiluting the sampled breath.

In accordance with an embodiment of the invention, there is provided abite block comprising an airway channel, wherein the airway channel isadapted to pass substantially free flow of breath and wherein a portionof the airway channel opens into a cavity adapted to receive an oralprong for sample breath from a patient. The cavity is further adapted toallow relative motion between the bite block and the prong withoutsubstantially reducing the breath sampling. Optionally, the bite blockfurther comprises an insertion channel adapted to pass substantiallyfree flow of breath, and to pass a medical instrument.

In accordance with some embodiments of the invention, the airway channelis adapted to pass substantially free flow of breath through a duct.Optionally, the duct is further adapted to enable a viewer to view theposition of an oral prong functionally connected to the bite block.

In accordance with some embodiments of the invention, the bite blockfurther comprises an oxygen channel located in proximity to the channel,wherein the oxygen channel is adapted to direct oxygen towards theinside of the mouth of a patient. Optionally, the airway channel isadapted to protrude further into the back of the mouth relative to theinsertion channel and/or said oxygen channel. Additionally oralternatively, the bite block is adapted to reduce the flow of oxygenfrom the oxygen channel into the airway channel, such that the oxygenpressure is adapted to be lower than the opposing pressure created bythe exhaled breath, so that the exhaled breath can push back out of themouth the oxygen, and at least partially prevent oxygen from reachingthe airway channel opening and consequently diluting the sampled breath.

In accordance with an embodiment of the invention, there is provided asystem for sampling breath, the system comprising: a bite blockcomprising an insertion channel and an airway channel, wherein theairway channel is adapted to pass substantially free flow of breath, andwherein said an insertion channel is adapted to pass substantially freeflow of breath and to pass a medical instrument; and a valve adapted toregulate oxygen delivery to the oxygen channel.

In accordance with some embodiments of the invention, the airway channelopens into a cavity adapted to receive an oral prong, wherein the oralprong is adapted to sample breath from a patient. Optionally, the cavityis further adapted to allow relative motion between the bite block andthe prong without substantially reducing the breath sampling.

In accordance with some embodiments of the invention, the airway channelis adapted to receive an oral prong, wherein the oral prong is adaptedto sample breath from a patient. Optionally, the airway channel isadapted to pass substantially free flow of breath through a duct.Additionally, the duct is further adapted to enable a viewer to view theposition of an oral prong functionally connected to said bite block.

In accordance with some embodiments of the invention, the system furthercomprises an oxygen channel located in proximity to the insertionchannel, wherein the oxygen channel is adapted to direct oxygen towardsthe inside of the mouth of a patient. Optionally, airway channel extendsfurther into the mouth relative to the insertion channel and/or theoxygen channel.

In accordance with some embodiments of the invention, there is provideda system for sampling breath, the system comprising: a bite blockcomprising an airway channel, wherein the airway channel is adapted topass substantially free flow of breath and wherein a portion of theairway channel opens into a cavity adapted to receive an oral prong forsampling breath from a patient, the cavity is further adapted to allowrelative motion between said bite block and said prong withoutsubstantially reducing the breath sampling; and a valve adapted toregulate oxygen delivery to said oxygen channel. Optionally, the systemfurther comprising an insertion channel adapted pass substantially freeflow of breath and to pass a medical instrument.

In accordance with an embodiment of the invention, there is provided asystem for sampling breath, the system comprising: a bite blockcomprising an insertion channel and an airway channel, wherein theairway channel is adapted to pass substantially free flow of breath andwherein the insertion channel is adapted to pass substantially free flowof breath and to pass a medical instrument; and an oral nasal cannulaadapted to sample breath.

BRIEF DESCRIPTION OF FIGURES

Examples illustrative of embodiments of the invention are describedbelow with reference to figures attached hereto. In the figures,identical structures, elements or parts that appear in more than onefigure are generally labeled with a same numeral in all the figures inwhich they appear. Dimensions of components and features shown in thefigures are generally chosen for convenience and clarity of presentationand are not necessarily shown to scale. The figures are listed below.

FIG. 1 schematically shows an isometric front view of an exemplary biteblock adapted for capnography and oxygen delivery to a patient, inaccordance with an embodiment of the invention;

FIG. 2 schematically shows an isometric back view of the exemplary biteblock in FIG. 1 in accordance with an embodiment of the invention;

FIG. 3 schematically shows an isometric front view of an exemplary biteblock comprising an oral nasal cannula and an oxygen tube;

FIG. 4 schematically shows an back view of the exemplary bite block inFIG. 3 in accordance with an embodiment of the invention; and

FIG. 5 schematically shows a cross-sectional view A-A of the exemplarybite block of FIG. 3, in accordance with an embodiment of the invention.

DETAILED DESCRIPTION

Reference is made to FIGS. 1 and 2 which schematically show an isometricfront view and back view, respectively, of an exemplary bite block 100adapted for passing a medical instrument, perform capnography and ifrequired, deliver oxygen to a patient, in accordance with an embodimentof the invention. Bite block 100 comprises an external section 101 andan oral insert, which may be refereed to as a mouthpiece 111. Mouthpiece111 is adapted to be placed inside a patient's mouth, while externalsection 101 is configured to be fitted over the mouth and tosubstantially restrict movement of the mouthpiece inside the patient'smouth. External section 101 comprises a main body portion 102, whichincludes an opening 104 to an insertion channel 134. Insertion channel134 is adapted to receive a medical instrument, for example anendoscope, which is inserted through opening 104 and extends throughinsertion channel 134 into a patient's mouth. Main body portion 102comprises a first lateral section 103 which laterally extends from oneside of main body portion 102 towards a first attachment 112. On theother side of main body portion 102, a second lateral section 105laterally extends towards a second attachment 113. First attachment 112and second attachment 113 comprise openings 114 and 115, respectively,the attachments adapted to receive a strap, or some other means offixing the bite block to a patient's mouth, generally by attaching thestrap, or other means, around the back of the head of the patient.Optionally, more than one strap or other means of attachment may be usedto fix the bite block to the patient's mouth.

Mouthpiece 111 comprises insertion channel 134, an airway channel 132and an oxygen channel 136. Insertion channel 134 extends from opening104 along a major portion of the length of the mouthpiece to an endopening 131. Insertion channel 134 is formed by a surface 145 which isusually supported by the tongue when the mouthpiece is inserted in thepatient's mouth, and a surface 143 which provides a biting surface forthe patient's lower teeth. Surfaces 145 and 143 are contoured withrounded edges to substantially reduce any possible harm to the patient'smouth and/or tongue, and/or patient discomfort, typically associatedwith sharp edges.

Protruding from first lateral section 103 is an oxygen tube adapter 108,adapted to receive an oxygen tube for orally administering oxygen to thepatient. Alternatively, oxygen tube adapter 108 may protrude from secondlateral section 105. Optionally, the oxygen tube adapter may protrudefrom first lateral section 103 and second lateral section 105, or fromother parts of bite block 100. Oxygen channel 136 extends from oxygentube adapter 108 laterally along a length of insertion channel 134.Oxygen channel 136 is adapted to conduct oxygen flowing into oxygen tubeadapter 108 through an opening 110, and through aperture 137 at theother end of oxygen channel 136, into the mouth of the patient.Optionally, oxygen channel 136 may extend the whole length of insertionchannel 134. Oxygen channel 136 is formed by a substantially curvedsurface 138 to reduce any possible harm to the patient's mouth and/ortongue, and/or patient discomfort, typically associated with sharpedges. In accordance with an embodiment of the invention, aperture 137is of a relative large diameter, generally in the range of 0.5-20 mm,for example, 2 mm, 3 mm, 5 mm, 8 mm, 12 mm, 15 mm, 18 mm, adapted tocreate a pressure decrease in the oxygen flow when flowing out of oxygenchannel 136 into the mouth of the patient. Optionally, oxygen channel136 may include more than one aperture. Additionally or alternatively,oxygen channel 136 may comprise one or more apertures, such as aperture137 in insertion channel 134 through which oxygen, or optionally aportion of the delivered oxygen, may flow out of the oxygen channel intothe patient's mouth.

In accordance with an embodiment of the invention, airway channel 132 isadapted to receive exhaled breath from the patient and to allow exhaledbreath and inhaled air to flow freely back and forth along the channel.The exhaled breath free flows along airway channel 132 in the directionof a cavity 142, included in the forward section of the airway channel.Airway channel 132 extends from cavity 142 in a direction inwardly, ordeeper, into the mouth of the patient a distance d compared to insertionchannel 134. The distance d is measured in a direction along an x-axisfrom an opening 135 comprised in airway channel 132 to opening 131 andgenerally ranges from 5 mm-20 mm, for example 5 mm, 8 mm, 12 mm, 16 mm,20 mm. In accordance with an embodiment of the invention, the pressureof the oxygen at opening 135 of airway channel 132 is less than thepressure of the opposing exhaled breath and therefore, oxygen issubstantially prevented from entering airway channel 132 and dilutingthe exhaled breath.

Airway channel 132 is formed by a substantially curved surface 140 whichmay slope upwards in the direction of the roof of the mouth when themouthpiece is inserted in the patient's mouth, and substantially curvedsurface 141 which provides a biting surface for the patient's upperteeth. Upward sloping of surface 140 allows for a larger opening 135 inairway channel 132 much like a funnel, opening 135 adapted to capturerelatively large amounts of exhaled breath. The funnel design of airwaychannel 132, provided by sloping surface 140, provides for substantialfree flow of breath in the airway channel. Surfaces 140 and 141 arecontoured with rounded edges to substantially reduce any possible harmto the patient's mouth and/or to reduce patient discomfort, typicallyassociated with sharp edges. In some embodiments of the invention, anopening may extend, partially or entirely, along the length betweenairway channel 132 and insertion channel 134.

In accordance with an embodiment of the invention the dimensions ofcavity 142 are such that they allow an oral nasal cannula (not shown) tomove, relative to bite block 100, linearly inside the cavity along thex-axis and/or y-axis and and/or z-axis, and/or angularly about the xand/or y and/or z axis, Relative motion of the oral nasal cannulasubstantially compensates for movement of bite block 100 relative to apatient's mouth, allowing oral nasal cannula to remain inserted incavity 142 generally at all times. Cavity 142 is formed from asubstantially vertical inner surface 144 of a section of main portion102, a section of first lateral section 103, and a section of secondlateral section 105. A border 146 perpendicularly extends from surface141 at the border of the airway channel 132 with cavity 142, andgenerally serves to demarcate the border between the mouthpiece and theexternal section. A cavity floor 148 comprises a surface adapted tosupport the oral nasal cannula when fitted into the cavity. Cavity 142further comprises a duct 106 in inner surface 144 adapted to allowexhaled breath and inhaled air to flow freely in and out of airwaychannel 132. Duct 106 may also be used by a viewer to view the positionof the oral nasal cannula inside the cavity.

Reference is made to FIG. 3 which schematically shows an isometric frontview of an exemplary bite block comprising an oral nasal cannula and anoxygen tube, to FIG. 4 which schematically shows a back view of theexemplary bite block in FIG. 3, and to FIG. 5 which schematically showsa cross-sectional view A-A of the exemplary bite block of FIG. 3 andFIG. 4, in accordance with an embodiment of the invention.

Bite block 200 is the same or substantially similar to bite block 100shown in FIGS. 1 and 2, additionally comprising an oral nasal cannula260 positioned inside cavity 242 and an oxygen tube 290, including avalve 291, attached to the bite block at an oxygen tube adapter 208.Bite block 200 comprises an external section 201, a mouthpiece 211, amain body portion 202, an opening 204, an insertion channel 234, a firstlateral section 203, a first attachment 212, a second lateral section205, a second attachment 213, openings 214 and 215, an airway channel232, an oxygen channel 236, an end opening 231, a surface 245, a surface243, oxygen channel 236, a curved surface 238, a cavity 242, an opening235, a curved surface 240, a curved surface 241, a vertical innersurface 244, a border 246, a cavity floor 248, and a duct 206, all thesame or substantially similar to that shown in FIGS. 1 and/or 2 at 101,111, 102, 104, 134, 103, 112, 105, 113, 114, 115, 132, 136, 131, 145,143, 136, 138, 142, 135, 140, 141, 144, 146, 148, and 106. It may beappreciated from FIG. 5 that curved surface 240 is a sloping surfaceextending from opening 231 to intersect curved surface 241, such that aheight h1 of airway channel 232 is a maximum at opening 231 anddecreases to a height h2 at the intersection with surface 241. Therelatively large opening in airway channel 232 allows for bettercollection of orally exhaled breath from the patient. Height h1 ofairway channel 232 is generally limited by the structure of the mouthand is typically in a range of 5-25 mm, for example, 10 mm, 14 mm, 16mm, or 20 mm. Height h2 of airway channel 232 is generally limited bythe size of the bite, and is typically in a range of 1-10 mm, forexample, 2 mm, 3.5 mm, or 5 mm. Optionally, heights h1 and h2 may be thesame.

Oxygen tube 290 is connected to bite block 200 by means of a rotationalnipple 274 which is inserted into oxygen tube adapter 208. Optionally,rotational nipple 274 is a fixed nipple not adapted for rotationalmotion. Oxygen, or some other type of breathable gas, is delivered tothe bite block through oxygen tube 290. The gas flows through the nippleinto oxygen tube adapter 208 and through oxygen channel 236 into apatient's mouth.

Valve 291 is adapted to regulate oxygen flow in the direction of oxygentube adapter 208 and oxygen channel 236, and in the direction of oralnasal cannula 260. Oxygen flow to oral nasal cannula 260 may bemaintained, when bite block 200 is removed, through a nasal oxygen tube(not shown) extending from valve 291 to opening 268 in oral nasalcannula 260.

Oral nasal cannula 260 comprises a main body 262 from which extend twonasal prongs 264 adapted to be inserted into the patient's nostrils forexhaled breath collection. The exhaled breath from the patient'snostrils flows through the nasal prongs into a breath conduit 276.Breath conduit 276 leads through main body 262 to an exit opening 269 towhich a breath sampling tube may be connected for delivering the exhaledbreath to a capnograph.

Main body 262 further comprises oxygen delivery holes such as, forexample hole 266, through which oxygen, or some other breathable gas,flows out of the main body into the patient's nostrils. The oxygen isdelivered to the oral nasal cannula through a nasal oxygen tube whichconnects to opening 268 at one end of the main body. Opening 268 leadsto a conduit 263 in main body 262 through which the oxygen flows to theoxygen delivery holes. Alternatively, opening 268 leads to a conduit263, through which oxygen may flow into prongs (not shown).

An oral prong 270 comprising a hollow tube with a cut-away tip 274 isattached to the bottom side of main body 262. In accordance with anembodiment of the invention oral prong 270 comprises a hollow oral prongextension 272 into which the oral prong may be slidingly inserted intoand retracted from, substantially extending the length of the oral prongwhen fully retracted. Optionally, oral prong 270 and oral prongextension 272 are fixed with respect to one another. Oral prongextension 272, comprises a hollow tube with a cut-away tip 273, and isadapted to be inserted into cavity 242.

Oral prong 270 is usually positioned in cavity 242 in a verticalposition along a y-axis, supported by an extended abutment of oral prongextension 272 with inner surface 244, and by an abutment of cut-away tip273 with cavity surface 248. Oral prong 270 is generally oriented suchthat an opening in cut-away tip 273 faces in the direction of airwaychannel 232. In accordance with an embodiment of the invention, oralprong 270 is adapted to sample the breath of a patient in airway channel232. Orally exhaled breath flowing through airway channel 232 may flowwith ease into oral prong extension 272 through cut-away tip 273, andinto oral prong 270 through cut-away tip 274. The orally exhaled breathflowing into oral prong 270 flows through the prong into conduit 276 inmain body 262 where it may combine with exhaled breath from thepatient's nostrils. The exhaled breath then flows out exit opening 269.

In accordance with an embodiment of the invention oral prong 270 isadapted to slide in a generally lateral direction, relative to biteblock 200, along a z-axis back and forth along the cavity floor 248, andto rotate and tilt relative to the y-axis substantially perpendicular tothe direction of sliding. A large degree of freedom in movement in oralprong 270, and thereby in oral nasal cannula 260, substantiallycompensates for movement of bite block 200 relative to a patient'smouth, allowing oral nasal cannula 260 to remain inserted in cavity 242generally at all times. In some embodiments of the invention, bite block200 comprises an airway channel 232 which includes an opening to whichoral prong 270 is affixed. Exhaled breath may then flow through theopening in airway channel 232 into oral prong 270.

In the description and claims of embodiments of the present invention,each of the words, “comprise” “include” and “have”, and forms thereof,are not necessarily limited to members in a list with which the wordsmay be associated.

The invention has been described using various detailed descriptions ofembodiments thereof that are provided by way of example and are notintended to limit the scope of the invention. The described embodimentsmay comprise different features, not all of which are required in allembodiments of the invention. Some embodiments of the invention utilizeonly some of the features or possible combinations of the features.Variations of embodiments of the invention that are described andembodiments of the invention comprising different combinations offeatures noted in the described embodiments will occur to persons withskill in the art. The scope of the invention is limited only by theclaims.

What we claim is:
 1. A bite block comprising: a front plate configuredto lodge against a patient's lips and forming a first opening and asecond opening; and a mouthpiece configured for insertion into thepatient's mouth, the mouthpiece comprising: an airway channel configuredto receive exhaled breath from the patient and to allow exhaled breathand inhaled air to flow freely back and forth along the channel when inuse, the airway channel extending from the second opening of the frontplate to an airway channel end; an insertion channel extending away fromthe first opening to an end of the insertion channel, the insertionchannel being formed by a wall having an inner surface and an externalsurface, wherein the insertion channel is configured to pass a medicalinstrument through the first opening and within the inner surface of thewall, wherein the insertion channel is positioned below a lower portionof the airway channel; a cavity orthogonal to and extending away from anupper portion of the airway channel and terminating in the upper portionof the airway channel at a location positioned between the secondopening and the airway channel end; and an oxygen channel extendingalong at least a part of the external surface of the wall, wherein theexternal surface of the wall defines at least a portion of an interiorsurface of the oxygen channel and a portion of an exterior wall of themouthpiece, wherein the wall completely separates the oxygen channelfrom the insertion channel such that there is no fluid communicationbetween the oxygen channel and the insertion channel along the wall, andwherein the oxygen channel is configured to deliver oxygen therethrough,wherein the airway channel is formed external to the inner surface ofthe wall, such that the airway channel is separated from the insertionchannel and the oxygen channel, and wherein the airway channel isconfigured to protrude further into the patient's mouth than the oxygenchannel and the insertion channel when in use, such that a distance ismaintained between the airway channel end and the end of the insertionchannel.
 2. The bite block of claim 1, wherein the airway channel isformed by a first substantially curved surface which slopes upwards inthe direction of the roof of the patient's mouth when the mouthpiece isinserted in the patient's mouth, and a second substantially curvedsurface, which is configured to provide a biting surface for thepatient's upper teeth.
 3. The bite block of claim 1, wherein the oxygenchannel is slanted downwards so that oxygen at least partially isprevented from reaching the airway channel end and consequently dilutingthe sampled breath.
 4. The bite block of claim 1, wherein the cavity ispositioned in a forward section of the bite block and configured so asto be external to the patient's mouth when in use, the cavity configuredto facilitate sampling of exhaled breath therefrom, when an oral prongis present in the cavity, and to allow ambient air and exhaled breath toflow in and out of the airway channel in the presence of the oral prongin the cavity.
 5. The bite block of claim 4, wherein the oral prongcomprises a third opening configured to face towards the flow of breathflowing along the airway channel.
 6. The bite block of claim 4, whereinthe cavity is further configured to allow relative lateral movementbetween the oral prong and the cavity, while maintaining the thirdopening of the oral prong facing towards the flow of breath flowingalong the airway channel.
 7. The bite block of claim 6, wherein thesecond opening allows exhaled breath and inhaled air to flowsubstantially freely back and forth along the airway channel.
 8. Thebite block of claim 7, wherein the second opening is further adapted toenable a viewer to view the position of the oral prong functionallyconnected to the bite block.
 9. The bite block of claim 1, wherein theinsertion channel comprises at least one aperture, the aperture being inthe wall of the insertion channel between the first opening and an endopening thereof, and wherein the oxygen channel is configured to deliveroxygen into the insertion channel through the at least one aperture,such that oxygen enters the insertion channel prior to the end openingthereof, thereby substantially preventing oxygen from the oxygen channelfrom entering the airway channel when in use.
 10. The bite block ofclaim 9, wherein the aperture is of a diameter configured to reduce theoxygen pressure to be lower than the opposing pressure created by theexhaled breath, so that oxygen at least partially is prevented fromreaching the airway channel opening and consequently diluting thesampled breath.
 11. A system for sampling breath, the system comprisinga bite block comprising: a front plate configured to lodge against apatient's lips; and a mouthpiece configured for insertion into thepatient's mouth, wherein the mouthpiece comprises: an airway channelconfigured to receive exhaled breath from a patient and to allow exhaledbreath and inhaled air to flow freely back and forth along the airwaychannel when in use; and terminating in a duct opening formed throughthe front plate; an insertion channel extending from a first opening ofthe insertion channel formed through the front plate along themouthpiece, the insertion channel formed by a wall having an innersurface and an external surface, wherein the insertion channel isconfigured to pass a medical instrument within the inner surface of thewall; an oxygen channel, wherein the oxygen channel is formed adjacentto the insertion channel such that the oxygen channel extends along atleast a part of the external surface of the wall of the insertionchannel, wherein the external surface defines at least a portion of aninterior surface of the oxygen channel and a portion of an exterior wallof the mouthpiece, wherein the wall completely separates the oxygenchannel from the insertion channel such that there is no fluidcommunication between the oxygen channel and the insertion channel alongthe wall the oxygen channel is configured to deliver oxygentherethrough, wherein the airway channel is configured to protrudefarther into the patient's mouth than the oxygen channel and theinsertion channel when in use, such that a substantial distance ismaintained between respective internal ends of the airway channel andthe insertion channel.
 12. The system of claim 11, wherein the airwaychannel is formed by a first substantially curved surface which slopesupwards in the direction of the roof of the patient's mouth when themouthpiece is inserted into the patient's mouth, and a secondsubstantially curved surface, which is configured to provide a bitingsurface for the patient's upper teeth.
 13. The system of claim 11,wherein the oxygen channel is slanted downwards so that oxygen at leastpartially is prevented from reaching the airway channel and consequentlydiluting the sampled breath.
 14. The system of claim 11, furtherincluding a cavity positioned in a forward section of the bite block andconfigured so as to be external to the patient's mouth when in use, thecavity is configured to facilitate sampling of exhaled breath therefrom,when an oral prong is present in the cavity, and to allow ambient airand exhaled breath to flow in and out of the airway channel in thepresence of the oral prong in the cavity.
 15. The system of claim 14,wherein the cavity is further configured to allow relative lateralmovement between the oral prong and the cavity, while maintaining anopening of the oral prong facing towards the flow of breath flowingalong the airway channel.
 16. The system of claim 11, wherein theinsertion channel comprises at least one aperture, the aperture being ina wall of the insertion channel between the first opening and an endopening thereof, and wherein the oxygen channel is configured to deliveroxygen into the insertion channel through the at least one aperture,such that oxygen enters the insertion channel prior to the end openingthereof, thereby substantially preventing oxygen from the oxygen channelfrom entering the airway channel when in use.
 17. The system of claim16, wherein the aperture is of diameter configured to reduce the oxygenpressure to be lower than the opposing pressure created by the exhaledbreath, so that oxygen at least partially is prevented from reaching theairway channel and consequently diluting the sampled breath.
 18. Thesystem of claim 11, further including a valve configured to regulateoxygen delivery from being supplied through to the oxygen channel tobeing supplied through an oral/nasal cannula such that, when in use,oxygen flow can be maintained, when the bite block is removed.